The present invention relates to the use of foamable compositions for packaging purposes. In a number of packaging applications, fragile articles or those otherwise needing protection from Undesired movement or breakage, particularly items with irregular shapes and sizes, have been packed in loose, friable or dunnage-type materials or in protective foamed polymer packaging materials, such as injection molded styrofoam, styrofoam chips, or other similar materials.
The present invention relates to foam-in-place packaging. Foam-in-place packaging is a useful alternative for packaging fragile or other items.
One technique for packaging articles in foam comprises generating the foam in place while the articles are being packaged. For example, when certain chemicals are mixed, they form polymeric products while at the same time generating gases, such as carbon dioxide and water vapor. If such chemicals are selected as being those that harden relatively quickly, they can be used to form hardened polymer foams in which the foam is produced by the gaseous carbon dioxide and water vapor leaving the mixture as it hardens. Typical foamable compositions include urethane precursors which, when mixed, generate polyurethane, carbon dioxide, and water vapor. As the urethane forms and hardens, these gases are concurrently generated so that by the time the urethane sets (generally a relatively short period of a few minutes or less) it takes the form of a polymer foam that has expanded to fill the void spaces in the container and to thereby cushion the item being packaged.
One technique for foam-in-place packaging is to place the object to be packaged in a container, cover it with a polymer film or other material which will protect it from liquids, inject a certain amount of foamable composition into the remainder of the container, and then close the container. As the composition foams, it fills the remainder of the container, forming a custom-shaped foam cushion surrounding the article.
For larger volume packaging operations, i.e., those requiring a number of foam protective packages to be made in relatively rapid succession, a number of automated devices have been developed and are assigned to the assignee of the present invention. Exemplary devices are described and claimed in U.S. Pat. Nos. 4,674,268; 4,800,708; and 4,854,109.
In other circumstances, however, the need for foam-in-place packaging still exists, but the use of automated machinery is unnecessary or undesired from a cost, efficiency, or other standpoint. In such circumstances, foam-in-place packaging can be accomplished with a supply of foamable chemicals, usually two, and an injection dispenser connected to the supplies of the respective chemicals. The chemicals are mixed within the gun to form the foamable composition. Examples of earlier versions of such guns include those described in U.S. Pat. Nos. 3,687,370; 3,945,569; 4,023,733; 4,159,079; and 4,426,023.
One of the more recently successful versions of such a hand-held packaging system is the INSTAPAK.RTM. 808/870 foam packaging systems from Sealed Air Corporation's Instapak Division in Danbury, Conn. The "808" system represented a significant improvement in hand-held devices, primarily because of its use of an electric motor, rather than a pneumatic pumping system, and its incorporation of a number of significant features that are the subjects of other commonly-assigned patents.
In an effort to enhance the 808 systems, however, various features were identified that could be subject to such improvement. For example, the hand-held dispenser or "gun" portion of the 808 system is formed of metal. The metal adds significant weight to the hand-held portion, a factor which can increase operator fatigue and tend to lower efficiency. Metal can also be more expensive than alternative materials, and requires particular tooling and fabricating equipment.
Additionally, the electric motor driving the 808 dispenser is located above the injection cartridge. As a result, in close circumstances, it can block the operator's view of the opening of the injection cartridge from which the foamable compositions exit.
Accordingly, in an effort to offer further improvements to this device, and to foam dispensers in general, there exists the need for a more ergonomically satisfactory dispenser, and one of reduced weight, and which maintains the significant advantages of the 808 system, but which offers significant improvements as well.